Merge an amended version of #630.

Fake stdout should always have an encoding attribute.

nose/plugins/capture.py

@@ -95,6 +95,15 @@ def addCaptureToErr(self, ev, output):
     def start(self):
         self.stdout.append(sys.stdout)
         self._buf = StringIO()
+        # Python 3's StringIO objects don't support setting encoding or errors
+        # directly and they're already set to None.  So if the attributes
+        # already exist, skip adding them.
+        if (not hasattr(self._buf, 'encoding') and
+                hasattr(sys.stdout, 'encoding')):
+            self._buf.encoding = sys.stdout.encoding
+        if (not hasattr(self._buf, 'errors') and
+                hasattr(sys.stdout, 'errors')):
+            self._buf.errors = sys.stdout.errors
         sys.stdout = self._buf
 
     def end(self):

unit_tests/test_capture_plugin.py

@@ -96,5 +96,12 @@ class Dummy:
             err = sys.exc_info()
         formatted = c.formatError(d, err)
 
+    def test_captured_stdout_has_encoding_attribute(self):
+        c = Capture()
+        c.start()
+        self.assertNotEqual(sys.stdout, sys.__stdout__)
+        self.assertTrue(hasattr(sys.stdout, 'encoding'))
+        c.end()
+
 if __name__ == '__main__':
     unittest.main()